The present invention relates to a liquid container which is suitably usable as an ink container mountable to an ink jet recording apparatus and which has a portion to be contacted to a filter when the ink is supplied to the outside, and to a liquid supplying system using the liquid container.
In the field of an ink jet recording, an ink jet cartridge integrally having an ink jet head and an ink container and detachably mountable to a recording device is used since it is convenient from the standpoint of compactness and maintenance-free. Such ink jet cartridge is a type in which the ink jet head and the ink container are always integral, and a type in which the ink jet head and the ink container are separate and integrated upon use.
In either of the types, the ink ink container is capable of producing a negative pressure (back pressure) against the ink flow toward the ink jet head to stably supply the ink into t ink jet head during recording operation and to stably retain the ink.
In order to produced the negative pressure, the use is generally made with a porous material such as urethane foam as a negative pressure generation member (ink absorbing material) using the capillary force of the porous material as disclosed in Japanese Laid-open Patent Application Hei 8-230207.
Referring to FIG. 8, there is shown an example of a conventional ink container using the capillary force of the porous material.
The ink container 110 shown in FIG. 8 comprises a casing 111 constituting an ink accommodating portion 116 for accommodating ink, and an ink absorbing material 118 in the ink accommodating portion 116 to absorb and retain the ink by the capillary force. The casing 111 comprises an ink supply port 114 for supplying the ink from the ink container 110 to the ink jet head 121, and an air vent 112 for introducing the ambience into the ink accommodating portion 116 to accomplish smooth ink supply to the ink jet head 121. In the ink supply port 114, an ink leading member 119 which is an additional ink absorbing material is press-contacted to the ink absorbing material 118. The ink leading member 119 is made of a unidirectional bundle of filers extending in a direction from the ink absorbing material 118 to the ink supply port 114, and the capillary force (ink retaining force) is higher than that of the ink absorbing material 118. As a result, the ink is stably supplied to the portion around the ink supply port 114, so that in the ink supply to the ink jet head 121 is stabilized.
The supply of the ink from the ink container 110 to the ink jet head 121 is effected by contacting the ink receiving tube 122 connected to the ink jet head 121 to the ink leading member 119. Here, free end of the ink receiving tube 122 is provided with a filter 123 mounted thereto to prevent entering of the foreign matter and/or bubble into the ink jet head 121 through the ink receiving tube 122.
However, the ink container with which the ink is supplied to the outside by contact or abutment of the filter to the ink absorbing material which retains the ink by capillary force.
As described hereinbefore, the ink absorbing material disposed at t ink supply port, namely, the ink leading member is an aggregate of fibers, and the ink is supplied through between the fibers. In order to enhance the ink retaining force, the gaps between the fibers are small. On the other hand, the filter having fine openings are generally used in order to prevent entrance of the foreign matter into the ink jet head.
Referring to FIG. 9(a), when an average pitch P2xe2x80x2 of the gap between the fibers of the ink leading member 114 in a plane of contact relative to the filter 123, is about mesh pitch P1xe2x80x2 of the opening of the filter 123, fibers of the ink leading member 114 enter the openings of the filter 123 when the filter 123 and the ink leading member 114 are contacted to each other, as shown in FIG. 9(b). Therefore, the state is as if the filter had a finer mesh pitch P3xe2x80x2 with the result of significant increase of the flow resistance against the ink.
With the recent increase of the recording speed of the ink jet recording apparatus, a high ink supply speed of the ink jet head is desired. The virtual existence of the structure impeding the ink flow in the ink supply path from the ink container to the ink jet head, the high speed recording of the ink jet recording apparatus is difficult. The foregoing analysis has been made with respect to the case of the ink absorbing material made of aggregate of the fibers. However, the analysis applies to the case of the porous material such as an urethane foam if the diameters of the pores of the porous material is considered as being the gaps between fibers. In the case that absorbing material absorbing and retaining the liquid is accommodated, and the absorbing material is contacted to the filter when the liquid is supplied to the outside, the same problem of ink supply arise when the liquid is to be supplied at high flow rate.
Accordingly, it is a principal object of the present invention to provide a liquid container and a liquid supplying system using the liquid container, in which an absorbing material absorbing and retaining the liquid is contacted by a filter when the liquid is supplied to the outside, and in which a stable supplying operation is possible even if the liquid is supplied at a high flow rate.
According to an aspect of the present invention, there is provided a liquid container comprising a container body; a liquid retaining member, provided in said container body, for absorbing and retaining liquid therein, said liquid retaining member having a surface to be contacted by a filter provided at a free end of liquid receiving means to supply the liquid to an outside, wherein said surface of said liquid retaining member is provided with pits and projections, the pits being out of contact with the filter, and the projections being contacted with the filter when said liquid retaining member and the filter are contacted.
According to the present invention, the contact region between the liquid holding member and the filter is limited because of the presence of the pits and projections on the surface of the liquid holding member relative to the filter. By this, the region where the flow resistance increases at the contact portion between the liquid holding member and the filter reduces, thus assuring the stabilized liquid supply at a large flow rate. If the pitch of the pits and projections is larger than the pitch of the opening of the filter, such pits and projections can be easily provided.
It is preferable that liquid retaining member includes a first liquid retaining member contactable to the filter and a second liquid retaining member, contacted to the first liquid retaining member, for supplying the liquid to the first liquid retaining member, the first liquid retaining member having a liquid retaining force which is larger than a liquid retaining force of the second liquid retaining member. By doing so, the liquid in the liquid container is easily retained around the reception means so that liquid is efficiently supplied from the liquid container.
In this case, by formation of the pits and projections at the contact surface between the first liquid retaining member and the second liquid retaining member, the pits and projections are engaged with the second liquid retaining member pulling, so that possible positional deviation between the first liquid retaining member and the second liquid retaining member is prevented. The first liquid retaining member may be made of fibers, preferably thermoplastic resin material, further preferably polyolefin resin material. If the fiber is made of thermoplastic resin material, the pits and projections are formed by contacting a member having a pattern of pits and projections corresponding to the pits and projections to be formed on the contacts surface of the liquid retaining member to the surface and heating and melting the contacts surface, thus transferring the pit-projection pattern. The fibers constituting the first liquid retaining member may be extended in a direction substantially perpendicular to a direction of contact of the first liquid retaining member to the filter.
According to another aspect of the present invention, there is provided a liquid supplying system comprising a liquid container having therein a liquid retaining member for absorbing and retaining liquid; liquid receiving means for receiving the liquid from said liquid container through a filter contacted to said liquid retaining member, pits and projections are formed on a surface of said liquid retaining member contactable to said filter or on said filter, the liquid retaining member and the filter being out of contact with each other at the pits and being contacted with each other at the projections.
According to the present invention, the contact region between the liquid holding member and the filter is limited because of the presence of the pits and projections on the surface of the liquid holding member relative to the filter. By this, the region where the flow resistance increases at the contact portion between the liquid holding member and the filter reduces, thus assuring the stabilized liquid supply at a large flow rate.
It is preferable that liquid retaining member includes a first liquid retaining member contactable to the filter and a second liquid retaining member, contacted to the first liquid retaining member, for supplying the liquid to the first liquid retaining member, the first liquid retaining member having a liquid retaining force which is larger than a liquid retaining force of the second liquid retaining member. The first liquid retaining member may be made of fibers, preferably thermoplastic resin material, further preferably polyolefin resin material. The liquid container and the liquid receiving means may be separable from each other.
Thus, according to the present invention, a surface of the liquid retaining member or the filter which are contactable to each other is provided with pits and projections which have such sizes that when they are connected, they are contacted to each other at the projections but not contacted at the pits, so that area of the high flow resistance portions are reduced, thus accomplishing stable liquid supply at a high flow rate.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.